[PATCH] IB: Fix race in sa_query
Use a copy of the id we'll return to the consumer so that we don't
dereference query->sa_query after calling send_mad(). A completion may
occur very quickly and end up freeing the query before we get to do
anything after send_mad().
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
index 276e1a5..5a08e81 100644
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -507,7 +507,13 @@
spin_unlock_irqrestore(&idr_lock, flags);
}
- return ret;
+ /*
+ * It's not safe to dereference query any more, because the
+ * send may already have completed and freed the query in
+ * another context. So use wr.wr_id, which has a copy of the
+ * query's id.
+ */
+ return ret ? ret : wr.wr_id;
}
static void ib_sa_path_rec_callback(struct ib_sa_query *sa_query,
@@ -598,14 +604,15 @@
rec, query->sa_query.mad->data);
*sa_query = &query->sa_query;
+
ret = send_mad(&query->sa_query, timeout_ms);
- if (ret) {
+ if (ret < 0) {
*sa_query = NULL;
kfree(query->sa_query.mad);
kfree(query);
}
- return ret ? ret : query->sa_query.id;
+ return ret;
}
EXPORT_SYMBOL(ib_sa_path_rec_get);
@@ -674,14 +681,15 @@
rec, query->sa_query.mad->data);
*sa_query = &query->sa_query;
+
ret = send_mad(&query->sa_query, timeout_ms);
- if (ret) {
+ if (ret < 0) {
*sa_query = NULL;
kfree(query->sa_query.mad);
kfree(query);
}
- return ret ? ret : query->sa_query.id;
+ return ret;
}
EXPORT_SYMBOL(ib_sa_mcmember_rec_query);